The gas systems in modern sporting rifles can be sensitive to variations in gas flow, pressure, and volume due to changes in ambient temperature, cartridges as they vary from propellant load to load or manufacturer to manufacturer, and/or the use of a suppressor. If there is insufficient gas flow from the barrel to the action in such a firearm, this can lead to short-stroking and misfeeds. On the other hand, a surplus of gas flow back to the action can lead to high action speeds causing forward ejection and trapped cases. In an attempt to regulate gas flow back to the action, some firearms have used a non-adjustable, fixed diameter gas port hole drilled through the barrel bore to establish a fluid connection with a gas tube so as to allow a fixed amount of gas flow back to the action. It is common for original equipment manufacturers to specify this gas port hole larger than would be needed for most available ammunition in order for the firearm to function reliably with the weakest of commercially available ammunition. This results in over-gassing of the firearm. If a suppressor were added to such a firearm, this would increase back pressure and likely lead to malfunctions due to excessive bolt speed.
Based on the inadequacies relating to a fixed diameter gas port holes, there is a need for a design that can optimize gas flow into the action for any given gas operated rifle in light of the numerous gas flow rates, pressures, and volumes realized as a result of variations in ambient temperature, various cartridge loadings, and/or use of a suppressor with the firearm.